1.  Complete the two OGT practice problems.  Be sure to explain your answer.  Turn it over when you are done.  This will count toward a grade.

2.  What is happening in the picture?  What is an ocean wave?  How is the surfer able to move with the wave?

3. Why are some surfers not able to stay up and ride out the wave? What causes ocean waves? Are there kinds of waves other than ocean waves? How are these wave like ocean waves?

4.  23.1 Nature of Waves  I can explain what a wave is in terms of energy.  I can identify a few examples of wave.  I can compare and contrast mechanical waves and electromagnetic waves.

5.  Radio  Light stick  Bridge  The Tacoma Narrows Bridge Collapse (1940) The Tacoma Narrows Bridge Collapse (1940)

6.  A wave is an traveling disturbance that carries energy from one place to another.  If you poke a floating ball, it oscillates (vibrates) up and down.  The oscillation (vibration) spreads outward from where it started.  Vibration is movement that follows the same path repeatedly.

7.  Energy is the ability to do work or cause change.  Vibrating objects are moving and have energy.  When you drop a ball into water, some of the water is pushed aside and raised by the ball.

8.  Waves are a traveling form of energy because they can change motion.  Waves also carry information, such as sound, pictures, or even numbers.  Vibration of your eardrum allows you to be able to hear sound waves.

10.  The matter through which a wave is transmitted is a medium. ◦ Water is the medium for ocean waves. ◦ Air is the medium for sound waves.  Solids, liquids and gases can act as a medium.  Mechanical waves require a medium.

11.  Not all waves require a medium.  Transmitted through a vacuum and disturb electric and magnetic fields  These waves are called electromagnetic waves  Examples: Light from the sun can travel to the Earth through the vacuum of space.  Microwaves in an oven and x-ray us in medicine.

12.  23.1 Nature of Waves  I can explain what a wave is in terms of energy.  I can identify a few examples of wave.  I can compare and contrast mechanical waves and electromagnetic waves. Chapter Twenty-Three: Waves

13. 23.2 Characteristics of Waves I can define wavelength, frequency, and amplitude. I can compare the characteristics of waves.

15.  You can think of a wave as a moving series of high points and low points.  A crest is the high point of the wave.  A trough is the low point. Characteristics of Waves

16.  Amplitude is the maximum movement from rest.  Amplitude indicates the amount of energy carried by they wave.  Increase in energy, give an increase in amplitude.  Measure from resting position to crest or resting position to trough. Resting Position

17.  Wavelength is the distance from any point on a wave to the same point on the next cycle of the wave.  The distance between one crest and the next crest is a wavelength.  Measured in meters (m) or centimeters (cm).  Symbol is the greek letter lambda (λ).

18.  The frequency of a wave is number of complete waves per unit of time.  Units are hertz (Hz).  1 Hz = 1 wave/sec  The faster something vibrates, the higher the frequency.

19.  If six complete vibrations occur in 2.0 seconds, what is the frequency of the wave?  If ten complete vibrations occur in 20 seconds, what is the frequency of the wave?

20.  λ= wavelength measured in (m) meters  f = frequency = time/cycle measured in (Hz) hertz

22. 23.2 Characteristics of Waves I can define wavelength, frequency, and amplitude. I can compare the characteristics of waves.

23. Terms to Know WaveCrest VibrationTrough MediumAmplitude Mechanical waveWavelength Electromagnetic waveFrequency * Make flashcards for the term*

24. Bookwork  Section 23-1 Page 591 ◦ #1-5  Section 23-2 Page 594 ◦ # 1-4

25.  Complete the two OGT practice problems.  Be sure to explain your answer.  Turn it over when you are done.  This will count toward a grade. Bell Work

26. 23.3 Types of Waves  I can classify waves as transverse, longitudinal, or surface waves.  I can cite examples of each type of wave.  I can distinguish between compressions and rarefactions.

27.  Depending on the motion of the medium as compared to the movement of the wave, waves are classified as either transverse or longitudinal. Types of Waves

28.  Motion of the medium is at right angles to the direction of the wave.  Particles move up and down (vertical), while movement of wave is across (horizontal).  Light and other electromagnetic waves Transverse Waves

30.  Compressions – space in the medium in which the particles are crowded together.  Rarefaction – space in the medium in which there are fewer particles. Longitudinal Waves

31.  Longitudinal waves consists of a series of compressions and rarefactions.  The motion of the medium is parallel to the direction of the wave.  The particles of the medium move in the same direction in which the wave moves.  Sound waves

32.  Wavelength of longitudinal waves is the distance between compressions or rarefactions.  Frequency is the number of compressions that pass a point per second.

34.  Some waves cannot be described as only transverse or longitudinal but a combination of both.  Example: Surface waves (between water and air)  They travel through two mediums.  Particles move in a circle instead of vertical or horizontal motion.

35.  I can classify waves as transverse, longitudinal, or surface waves.  I can cite examples of each type of wave.  I can distinguish between compressions and rarefactions.

36. Transverse Wave Longitudinal Wave Surface Wave * Make flashcards for the term*

37.  Section 23-3 Page 597 ◦ #1-5

38.  Complete the two OGT practice problems.  Be sure to explain your answer.  Turn it over when you are done.  This will count toward a grade. Bell Work

39.  I can predict increases or decreases in wavelength for a given increase or decrease in frequency.  I can relate speed, frequency, and wavelength.  I can solve mathematical problems involving speed of waves.

40.  The speed of a water wave is how fast the wave spreads, NOT how fast the water surface moves up and down or how fast the dropped ball moves in the water. How do we measure the wave speed? Speed of Waves

41.  The speed is the number of waves passing a point in a certain amount of time (frequency) and the wavelength.  Speed = Frequency X Wavelength  Speed is measured in meters per second (m/s).  A wave with a frequency of 4Hz (1/s) and a wavelength of 2m has a speed of 8m/s. ◦ 4Hz X 2m = 8m/s Speed of Waves

42.  In a given medium, the speed of a wave is constant (does not change).  Increase in frequency, means a decrease in wavelength.  Speed of a wave only depends upon the medium through which it is traveling.

43.  Density of the medium affects the speed of mechanical waves. ◦ A wave moves slower through a medium with higher density. ◦ It is harder to get all the particles of a denser medium to move the energy through.  Elasticity also affects speed of waves. ◦ Elasticity is the ability of a medium to return quickly to its original shape after being disturbed. ◦ Waves move faster in a more elastic medium.

45.  The wavelength of a wave on a string is 1 meter and its frequency is 5 Hz. ◦ Calculate the wave speed  The frequency of a wave on a string is 2 Hz and the wavelength is 4 meters. ◦ Calculate the wave speed Calculating Wave Speed

46.  I can predict increases or decreases in wavelength for a given increase or decrease in frequency.  I can relate speed, frequency, and wavelength.  I can solve mathematical problems involving speed of waves.

47.  Section 23-4 Page 599 ◦ #1-5

48.  Complete the two OGT practice problems.  Be sure to explain your answer.  Turn it over when you are done.  This will count toward a grade. Bell Work

49.  I can identify examples of each type of wave interaction.  I can explain some common phenomena based on wave interaction. 23.5 Interactions of Waves

50.  When a wave encounters a surface, four interactions can occur: 1. reflection 2. refraction 3. diffraction 4. interference 4 Interactions of Waves

51. Interference – When two waves meet a the same place, either constructive or destructive occurs Interactions

52.  A boundary is an edge or surface where things change.  Reflection, refraction, and diffraction usually occur at boundaries. Changing Mediums

53.  Reflection is the bouncing back of a wave after it strikes a boundary that does not absorb all of the wave’s energy.  A line drawn in the direction of motion of a wave is called a ray.  Incident wave is the incoming wave.  Reflected wave is the wave bouncing back.

54.  Angle of incidence (i) – formed by the incident ray and the imaginary normal line.  Angle of reflection (r) - formed by the reflected ray and the imaginary normal line. Law of reflection – the angle of incidence (i) is equal to the angle of reflection (r).

55.  Waves travel straight until they hit a new medium.  Refraction – the bending of waves due to a change in speed (different speeds through different mediums)

56.  Diffraction – bending of waves around the edge of an obstacle.   When a plane wave passes through a small hole diffraction turns it into a circular wave. Diffraction Interactions

57.  Interference – when two or more waves arrive at the same place at the same time.  There are two type of interference: constructive and destructive Interference

58.  Constructive interference happens if waves combine in such a way that the disturbance that results is greater than either wave alone.  Crests of the two waves add together to form a single wave.  The amplitude is of the single wave is equal to the sum of the amplitudes of the two original waves.

60.  Destructive interference – waves combine in such a way that the disturbance that results is less than either wave alone.  Crests and troughs combine by subtracting from each other to form a single wave.  If the crest of one wave occurs at the trough of the other wave and both waves have the same amplitude, the waves will cancel each other out. Destructive Interference

62. Standing Waves  Vibrating the a rope at just the right frequency can cause a standing wave.  Standing waves do not appear to be moving.  Nodes are where destructive interference results in no energy displacement.  Antinodes are where constructive interference causes maximum energy displacement (any crest or trough).

63. Standing Waves  The frequency at which a standing wave occurs is called natural frequency or resonant frequency.  Less effort is required to achieve a large amplitude at its natural frequency.  Resonance is the ability of an object to vibrate by absorbing energy of its own natural frequency.  Singer can shatter glass by singing at the same natural frequency that a glass has. Glass is not flexible and when it absorbs the energy it breaks.

64.  I can identify examples of each type of wave interaction.  I can explain some common phenomena based on wave interaction. 23.5 Interactions of Waves

65. ReflectionsRefraction DiffractionInterference Standing WaveResonant Frequency * Make flashcards for the term*

66.  Section 23-5 Page 606 ◦ #1-6  Chapter Review Page 610 ◦ Multiple Choice #1-9 ◦ True/False #1-8 ◦ Concept Mastery #1-3, 5-9

67. Cell Phones: How they work The process that allows a cell phone to communicate is the same as for a radio or walkie-talkie. All of these devices use electromagnetic waves of within a specific frequency range to send information.